Low friction coatings with improved abrasion and wear properties and methods of making

Abstract

Provided are low friction coatings with improved abrasion, wear resistance and methods of making such coatings. In one form, the coating includes: i) an under layer selected from the group consisting of CrN, TiN, TiAlN, TiAlVN, TiAlVCN, TiSiN, TiSiCN, TiAlSiN and combinations thereof, wherein the under layer ranges in thickness from 0.1 to 100 μm, ii) an adhesion promoting layer selected from the group consisting of Cr, Ti, Si, W, CrC, TiC, SiC, WC, and combinations thereof, wherein the adhesion promoting layer ranges in thickness from 0.1 to 50 μm and is contiguous with a surface of the under layer, and iii) a functional layer selected from the group consisting of a fullerene based composite, a diamond based material, diamond-like-carbon and combinations thereof, wherein the functional layer ranges from 0.1 to 50 μm and is contiguous with a surface of the adhesion promoting layer.

What is claimed is: 
     
       1. A multi-layer low friction coating comprising:
 i) an under layer comprising CrN, wherein the under layer ranges in thickness from 5 to 15 μm, 
 ii) an optional adhesion promoting layer comprising CrC, wherein the adhesion promoting layer ranges in thickness from 5 to 15 μm and is contiguous with a surface of the under layer, and 
 iii) a functional layer comprising diamond-like-carbon (DLC), wherein the functional layer ranges from 5 to 15 μm and is contiguous with a surface of the optional adhesion promoting layer or a surface of the under layer, and wherein the diamond-like-carbon (DLC) is selected from the group consisting of ta-C, DLCH, and combinations thereof, 
 wherein the optional adhesion promoting layer is interposed between the under layer and the functional layer, 
 wherein the coefficient of friction of the functional layer of the low friction coating as measured by the block on ring friction test is less than or equal to 0.15, and 
 wherein the abrasion resistance of the low friction coating as measured by the modified ASTM G105 abrasion test yields a wear scar depth of less than or equal to 20 μm and a weight loss less than or equal to 0.02 grams. 
 
     
     
       2. The coating of  claim 1 , wherein the under layer is contiguous with a surface of a substrate. 
     
     
       3. The coating of  claim 2 , wherein the substrate is selected from the group consisting of steel, stainless steel, hardbanding, an iron alloy, an aluminum based alloy, a titanium based alloy, ceramics and a nickel based alloy. 
     
     
       4. The coating of  claim 3 , wherein the hardbanding comprises a cermet based material, a metal matrix composite or a hard metallic alloy. 
     
     
       5. The coating of  claim 1 , wherein the under layer hardness ranges from 800 to 3500 VHN. 
     
     
       6. The coating of  claim 1 , wherein the adhesion promoting layer hardness ranges from 200 to 2500 VHN. 
     
     
       7. The coating of  claim 1 , wherein the functional layer hardness ranges from 1000 to 7500 VHN. 
     
     
       8. The coating of  claim 1 , wherein the adhesion promoting layer is present, the coating further including a gradient at the interface of the under layer and the adhesion promoting layer ranging from 0.01 to 10 μm. 
     
     
       9. The coating of  claim 1 , wherein the adhesion promoting layer is present, the coating further including a gradient at the interface of the adhesion promoting layer and the functional layer ranging from 0.01 to 10 μm. 
     
     
       10. The coating of  claim 1 , wherein the adhesion promoting layer is present, the coating further including a second adhesion promoting layer comprising CrC, wherein the second adhesion promoting layer ranges in thickness from 0.1 to 2 μm and is contiguous with a surface of the functional layer, and a second functional layer comprising diamond-like-carbon (DLC), wherein the second functional layer ranges from 0.1 to 2 μm and is contiguous with a surface of the second adhesion promoting layer. 
     
     
       11. The coating of  claim 10 , wherein the diamond-like-carbon (DLC) is selected from the group consisting of ta-C, DLCH, and combinations thereof. 
     
     
       12. The coating of  claim 1 , wherein the surface roughness of the functional layer ranges from 0.01 μm to 1.0 μm Ra. 
     
     
       13. The coating of  claim 1 , wherein the abrasion resistance of the low friction coating as measured by the modified ASTM G105 abrasion test yields a wear scar depth and a weight loss at least 5 times lower than a single layer coating of the same functional layer. 
     
     
       14. The coating of  claim 1 , wherein the coating is applied to a portion of the surface of a device selected from the group consisting of a drill bit for subterraneous rotary drilling, a drill stem assembly for subterraneous rotary drilling, a casing, a tubing, couplings, a work string, a coiled tubing, a pipe, a riser, a plunger, centralizers, a completion string, a production string, and a petrochemical and chemical production device. 
     
     
       15. A method of making a multi-layer low friction coating comprising:
 i) providing a substrate for coating, 
 ii) depositing on a surface of the substrate an under layer comprising CrN, wherein the under layer ranges in thickness from 5 to 15 μm, 
 iii) depositing optionally on the surface of the under layer an adhesion promoting layer comprising CrC, wherein the adhesion promoting layer ranges in thickness from 5 to 15 μm and is contiguous with a surface of the under layer, and 
 iv) depositing on the surface of the optional adhesion promoting layer or on the surface of the under layer a functional layer comprising diamond-like-carbon (DLC), wherein the functional layer ranges from 5 to 15 μm and is contiguous with a surface of the optional adhesion promoting layer or a surface of the under layer, and wherein the diamond-like-carbon (DLC) is selected from the group consisting of ta-C, DLCH, and combinations thereof, 
 wherein the coefficient of friction of the functional layer of the low friction coating as measured by the block on ring friction test is less than or equal to 0.15, and 
 wherein the abrasion resistance of the low friction coating as measured by the modified ASTM G105 abrasion test yields a wear scar depth of less than or equal to 20 μm and a weight loss less than or equal to 0.02 grams. 
 
     
     
       16. The method of  claim 15 , further including depositing from 1 to 100 series of incremental coating layers, wherein each series of incremental coating layers includes a combination of an incremental adhesion promoting layer, an incremental functional layer and an optional incremental under layer, wherein the each series of incremental coating layers is configured as follows:
 (i) wherein the optional incremental under layer is selected from the group consisting of CrN, TiN, TiAlN, TiAlVN, TiAlVCN, TiSiN, TiSiCN, TiAlSiN and combinations thereof; ranges in thickness from 0.1 to 100 μm; and is contiguous with a surface of the functional layer and the incremental adhesion promoting layer; wherein the optional incremental under layer is interposed between the functional layer and the incremental adhesion promoting layer, 
 (ii) wherein the incremental adhesion promoting layer is selected from the group consisting of Cr, Ti, Si, W, CrC, TiC, SiC, WC, and combinations thereof; ranges in thickness from 0.1 to 50 μm; and is contiguous with a surface of the functional layer or optional incremental under layer, and the incremental functional layer;
 wherein the incremental adhesion promoting layer is interposed between the functional layer and the incremental functional layer or between the optional incremental under layer and the incremental functional layer 
 
 (iii) wherein the incremental functional layer is selected from the group consisting of a fullerene based composite, a diamond based material, diamond-like-carbon (DLC), and combinations thereof; ranges from 0.1 to 50 μm in thickness; and is contiguous with a surface of the incremental adhesion promoting layer. 
 
     
     
       17. The method of  claim 15 , wherein the substrate is selected from the group consisting of steel, stainless steel, hardbanding, an iron alloy, an aluminum based alloy, a titanium based alloy, ceramics and a nickel based alloy. 
     
     
       18. The method of  claim 17 , wherein the hardbanding comprises a cermet based material, a metal matrix composite or a hard metallic alloy. 
     
     
       19. The method of  claim 15 , wherein the under layer hardness ranges from 800 to 3500 VHN. 
     
     
       20. The method of  claim 15 , wherein the adhesion promoting layer hardness ranges from 200 to 2500 VHN. 
     
     
       21. The method of  claim 15 , wherein the functional layer hardness ranges from 1000 to 7500 VHN. 
     
     
       22. The method of  claim 15 , further including a gradient at the interface of the under layer and the adhesion promoting layer ranging from 0.01 to 10 μm. 
     
     
       23. The method of  claim 15 , further including a gradient at the interface of the adhesion promoting layer and the functional layer ranging from 0.01 to 10 μm. 
     
     
       24. The method of  claim 16 , wherein the incremental functional layer is diamond-like-carbon (DLC). 
     
     
       25. The method of  claim 24 , wherein the diamond-like-carbon (DLC) is selected from the group consisting of ta-C, ta-C:H, DLCH, PLCH, GLCH, Si-DLC, N-DLC, O-DLC, B-DLC, Me-DLC, F-DLC and combinations thereof. 
     
     
       26. The method of  claim 16 , wherein the optional incremental under layer hardness ranges from 800 to 3500 VHN. 
     
     
       27. The method of  claim 16 , wherein the incremental adhesion promoting layer hardness ranges from 200 to 2500 VHN. 
     
     
       28. The method of  claim 16 , wherein the incremental functional layer hardness ranges from 1000 to 7500 VHN. 
     
     
       29. The method of  claim 16 , further including a gradient at the interface of the optional incremental under layer and the incremental adhesion promoting layer ranging from 0.01 to 10 μm. 
     
     
       30. The method of  claim 16 , further including a gradient at the interface of the incremental adhesion promoting layer and the incremental functional layer ranging from 0.01 to 10 μm. 
     
     
       31. The method of  claim 15 , wherein the surface roughness of the functional layer ranges from 0.01 μm to 1.0 μm Ra. 
     
     
       32. The method of  claim 16 , wherein the surface roughness of the outermost incremental functional layer ranges from 0.01 μm to 1.0 μm Ra. 
     
     
       33. The method of  claim 15 , wherein the counterface wear scar depth as measured by the block on ring friction test is less than or equal to 500 μm. 
     
     
       34. The method of  claim 15 , wherein the abrasion resistance of the low friction coating as measured by the modified ASTM G105 abrasion test yields a wear scar depth and a weight loss at least 5 times lower than a single layer coating of the same functional layer. 
     
     
       35. The method of  claim 15  or  16 , wherein the substrate is a portion of the surface of a device selected from the group consisting of a drill bit for subterraneous rotary drilling, a drill stem assembly for subterraneous rotary drilling, a casing, a tubing, couplings, a work string, a coiled tubing, a pipe, a riser, a plunger, centralizers, a completion string, a production string, and a petrochemical and chemical production device. 
     
     
       36. The method of  claim 15 , wherein the steps of depositing the under layer, depositing the adhesion promoting layer or depositing the functional layer are selected from the group consisting of physical vapor deposition, plasma assisted chemical vapor deposition, and chemical vapor deposition. 
     
     
       37. The method of  claim 36 , wherein the physical vapor deposition coating method is selected from the group consisting of magnetron sputtering, ion beam assisted deposition, cathodic arc deposition and pulsed laser deposition. 
     
     
       38. The method of  claim 15 , further including a post-processing step on the functional layer to achieve a surface roughness between 0.01 to 1.0 μm Ra. 
     
     
       39. The method of  claim 38 , wherein the post-processing step is selected from the group consisting of mechanical polishing, chemical polishing, depositing of smoothening layers, an ultra-fine superpolishing process, a tribochemical polishing process, an electrochemical polishing process, and combinations thereof.